Test if the ignore rules apply to a given file.
This function simply checks the ignore rules to see if they would apply to the given file. Unlike git_status_file(), this indicates if the file would be ignored regardless of whether the file is already in the index or in the repository.
the file to check ignores for, rooted at the repo's workdir
boolean returning 0 if the file is not ignored, 1 if it is
GIT_SUCCESS if the ignore rules could be processed for the file (regardless of whether it exists or not), or an error < 0 if they could not.